[BUG] Internal DMIC on Framework 13 AMD (Ryzen AI 300, ACP7.0) captures only silence — bound to legacy acp_mach, not SOF #5944

Bug description

The internal digital microphone (DMIC) on a Framework Laptop 13 AMD (Ryzen AI 300 series) produces completely silent capture. arecord completes without any error and produces a correctly-sized/formatted WAV file, but the file contains only silence, and no errors, warnings, or firmware messages appear in dmesg at any point during the capture.

Notably, the DMIC card is bound to the legacy snd_acp_legacy_mach / acp_mach driver rather than the SOF DSP path — even though snd_sof_amd_acp70 and alsa-sof-firmware are both present on the system. It's unclear whether this platform is expected to use the SOF path for DMIC and isn't being matched correctly, or whether the legacy path is expected here and has its own DMIC bug.

Reproducing

sudo dmesg -C
arecord -D hw:3,0 -f S32_LE -r 48000 -c 2 -d 5 test.wav
paplay test.wav      # silent
sudo dmesg | grep -iE "acp|pdm|sof|pcm"   # no output at all

This bypasses PipeWire/WirePlumber entirely, ruling out a userspace configuration issue.

A separate, unrelated bug on the same machine — the codec card (c1:00.6, HD Audio) defaulting to a broken HiFi (Headset, Mic1, Speaker) UCM profile that silently fails to capture — was fixed by disabling UCM in WirePlumber. That fix is unrelated to this DMIC card, which is a distinct PCI device (c1:00.5) and driver.

Environment

• Device: Framework Laptop 13, AMD Ryzen AI 300 series
• ALSA card longname: Framework-Laptop13AMDRyzenAI300Series-A9-FRANMGCP09
• Distro: Fedora 44
• Kernel: 7.2.5-200.fc44.x86_64
• BIOS/EC firmware version: 04.02
• alsa-utils: 1.2.16-1.fc44
• alsa-sof-firmware: 2025.12.2-1.fc44 (installed but not bound to this card)
• DMIC card: card 3: acppdmmach [acp-pdm-mach], PCI 0000:c1:00.5, driver acp_mach / module snd_acp_legacy_mach
• HD Audio codec card (unrelated UCM issue, already resolved): PCI 0000:c1:00.6 [1022:15e3]

Attachments

alsa-info.txt